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OS/2 Shareware BBS: 8 Other
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OS/2 Help File
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1998-04-20
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7KB
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147 lines
ΓòÉΓòÉΓòÉ 1. Configuring a dBASE Data Source ΓòÉΓòÉΓòÉ
Data Source Name:
A string that identifies this dBASE data source configuration in
ODBC.INI. Examples include "Accounting" or "dBASE Files."
Description:
An optional long description of a data source name. For example, "My
Accounting Database" or "dBASE files in C:\ACCOUNTS."
Database Directory:
A path specification to the directory that contains the database
files. If none is specified, the current working directory is used.
The following values are optional:
Create Type:
The type of table or index to be created on a Create Table or Create
Index statement. Select dBASE III, dBASE IV, dBASE V, Clipper,
FoxBASE, FoxPro1, or FoxPro25. The default is dBASE V. dBASE II is
not supported for OS/2.
Lock Compatibility:
The locking scheme the driver uses when locking records. Select
dBASE, Q+E, Q+EVirtual, Clipper, or Fox. The default is dBASE. These
values determine locking support as follows:
ΓûádBASE specifies Borland-compatible locking.
ΓûáQ+E specifies that locks be placed on the actual bytes occupied by
the record. Only applications that use the dBASE driver can read and
write to the database. Other applications are locked out of the
table completely (they cannot even read other records). This locking
is compatible with earlier versions of Q+E products.
ΓûáQ+EVirtual specifies that locks be placed on bytes beyond the
physical end-of-file. Q+EVirtual is the same as Q+E except that
other applications can open the table and read the data.
The advantage of using a Q+E locking scheme over dBASE locking is
that, on Inserts and Updates, Q+E locks only individual index tags,
while dBASE locks the entire index.
ΓûáClipper specifies Clipper-compatible locking.
ΓûáFox specifies FoxPro- and FoxBASE-compatible locking.
If you are accessing a table with an application that uses the dBASE
driver, your locking scheme does not have to match the Create Type.
However, if you are accessing a table with two applications, and only
one uses the dBASE driver, set your locking scheme to match the other
application. For example, you do not have to set this value to Fox
to work with a FoxPro table. But if you are using a FoxPro
application simultaneously with an application using the dBASE driver
on the same set of tables, set this value to Fox to ensure that your
data does not get corrupted.
Locking:
The level of locking for the database file (FILE, RECORD, or NONE).
FILE locks all of the records in the table. RECORD (the default)
locks only the records affected by the statement. NONE offers the
best performance but is intended only for single-user environments.
File Open Cache:
A numeric value to specify the maximum number of unused file opens to
cache. For example, the value 4 specifies that when a user opens and
closes four tables, the tables are not actually closed. The driver
keeps them open so that if another query uses one of these tables,
the driver does not have to perform another open, which is expensive.
The advantage of file open caching is increased performance. The
disadvantage is that a user who specifies file locking on open may
get a locking conflict even though no one appears to have the file
open. The default is 0, which means no file open caching.
Cache Size:
The amount of memory, in 64K blocks, that the driver uses to cache
database records. The higher the number, the better the performance.
The maximum number you can set depends on the system memory
available. This value must be a multiple of 64. The default is
256K. If the cache size is greater than 0, when browsing backwards,
you will not be able to see updates made by other users until you
reexecute the Select statement.
International Sort:
A setting to indicate the order in which records are retrieved when
you issue a Select statement with an Order By clause. Select this
check box to use the international sort order as defined by your
operating system. International sort order is case-insensitive (a
precedes B); the sorting of accented characters is also affected (see
your operating system documentation). Leave this box blank to use
the ASCII sort order. ASCII sort order is case-sensitive, where
uppercase letters precede lowercase letters (B precedes a).
Use Long Names:
A setting that enables the driver to use long filenames as table
names. If you select this check box, the maximum table name length is
128 characters.
Use Long Qualifiers:
A setting that enables the driver to use long pathnames as table
qualifiers. When you set this check box, pathnames can be up to 249
characters. The default length for pathnames is 128 characters.
Define
Displays the Define File dialog box to let you select an index file, and then
displays the Define File dialog box.
Translate
Displays the Select Translator dialog box to allow you to perform a
translation of your data from one character set to another. Choose the
INTERSOLV OEM ANSI translator to translate your data from the IBM PC character
set to the ANSI character set
ΓòÉΓòÉΓòÉ 2. Defining Index Attributes ΓòÉΓòÉΓòÉ
To define the index files that are associated with a dBASE file:
1. Click Define in the dBASE setup dialog box, which you can access through
the ODBC Administrator. The standard file open dialog box for your system
appears.
2. Select a dBASE file and click OK to define the special indexes using the
Define Table dialog box.
3. The upper section of the dialog box displays the directory name and
filename that contains the data file. Translation box.
4. The lower section of the dialog box displays the index information for the
data file. The Index File drop-down list lets you select any index file in
the database directory. If the index file is in a different directory, you
must provide the full pathname.
Select the Maintain check box to associate this index file with your dBASE
file.
To specify that an index file is unique, select the Unique check box that
appears at the right of the index filename.
5. If the selected index has an .MDX or .CDX extension, you cannot mark the
index file as unique. Instead, you may mark the tags within the index as
unique. To do so, select the tag name in the Tag drop-down list and select
the Unique check box that appears at the right of the tag name.